Android:How to Read File in Bytes

Android : How to read file in bytes?

here it's a simple:

File file = new File(path);
int size = (int) file.length();
byte[] bytes = new byte[size];
try {
    BufferedInputStream buf = new BufferedInputStream(new FileInputStream(file));
    buf.read(bytes, 0, bytes.length);
    buf.close();
} catch (FileNotFoundException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

Add permission in manifest.xml:

 <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Android | How Read file to byte array?

To read a File you would be best served with a FileInputStream.

You create a File object pointed to your file on the device. You open the FileInputStream with the File as a parameter.

You create a buffer of byte[]. This is where you will read your file in, chunk by chunk.

You read in a chunk at a time with read(buffer). This returns -1 when the end of the file has been reached. Within this loop you must do the work on your buffer. In your case, you will want to send it using your protocol.

Do not try to read the entire file at once otherwise you will likely get an OutOfMemoryError.

File file = new File("input.bin");
FileInputStream fis = null;
try {
    fis = new FileInputStream(file);

    byte buffer[] = new byte[4096];
    int read = 0;

    while((read = fis.read(buffer)) != -1) {
        // Do what you want with the buffer of bytes here.
        // Make sure you only work with bytes 0 - read.
        // Sending it with your protocol for example.
    }
} catch (FileNotFoundException e) {
    System.out.println("File not found: " + e.toString());
} catch (IOException e) {
    System.out.println("Exception reading file: " + e.toString());
} finally {
    try {
        if (fis != null) {
            fis.close();
        }
    } catch (IOException ignored) {
    }
}

Elegant way to read file into byte[] array in Java

A long time ago:

Call any of these

byte[] org.apache.commons.io.FileUtils.readFileToByteArray(File file)
byte[] org.apache.commons.io.IOUtils.toByteArray(InputStream input) 

From

http://commons.apache.org/io/

If the library footprint is too big for your Android app, you can just use relevant classes from the commons-io library

Today (Java 7+ or Android API Level 26+)

Luckily, we now have a couple of convenience methods in the nio packages. For instance:

byte[] java.nio.file.Files.readAllBytes(Path path)

Javadoc here

Reading a resource sound file into a Byte array

You do have byte array length as you can see:

 InputStream inStream = context.getResources().openRawResource(R.raw.cheerapp);
 byte[] music = new byte[inStream.available()];

And then you can read whole Stream into byte array easily.

Of course I would recommend that you do check when it comes to the size and use ByteArrayOutputStream with smaller byte[] buffer if needed:

public static byte[] convertStreamToByteArray(InputStream is) throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    byte[] buff = new byte[10240];
    int i = Integer.MAX_VALUE;
    while ((i = is.read(buff, 0, buff.length)) > 0) {
        baos.write(buff, 0, i);
    }

    return baos.toByteArray(); // be sure to close InputStream in calling function
}

If you'll be doing lots of IO operations I recommend that you make use of org.apache.commons.io.IOUtils. That way you won't need to worry too much about quality of your IO implementation and once you import JAR into your project you would just do:

byte[] payload = IOUtils.toByteArray(context.getResources().openRawResource(R.raw.cheerapp));

Android - How to properly parse a file consisting of bytes delimited with space?

String.getBytes not the same as Bytes.toString. When you convert byte to string you receive number of chars, for example byte value 127 is 3 char ['1','2','7'] with byte codes [49, 50, 55]

    byte b = 127;

    System.out.println(b + ""); // 127

String "127".getBytes() returns this array [49, 50, 55]

    System.out.println(Arrays.toString("127".getBytes())); // [49, 50, 55]

To properly read value you need next code:

    byte[] bytes = "127".getBytes();

    String value = "";
    for (byte part : bytes) {

        value += (char)part;
    }

    System.out.print(value); // 127

If you want to receive byte value you need parse this string via

    byte b = Byte.parseByte(value);

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